Process for the preparation of Pyraclostrobin

Abstract

The present invention relates to a novel and improved process for preparation of methyl [2-({[1-(4-chlorophenyl)-1H-pyrazol-3-yl]oxy}methyl)phenyl]methoxycarbamate (Pyraclostrobin) of formula (I) in free form or in agrochemically acceptable salt form useful as a pest control agent starting from methyl [2-({[1-(4-chlorophenyl)-1-H-pyrazol-3-yl]oxy}methyl)phenyl]hydroxycarbamatein simple manner and in high purity and good yield.

The invention claimed is: 
     
       1. An improved process for the preparation of methyl [2-({[1-(4-chlorophenyl)-1H-pyrazol-3-yl] oxy} methyl) phenyl]methoxycarbamate (Pyraclostrobin) of formula (I) 
       
         
           
           
               
               
           
         
         comprising the steps of:
 i) reacting compound of formula (II) with methylating agent selected from Methyl chloride or Methyl bromide in presence of a catalyst and acid binding agent selected from the group consisting of: Potassium Carbonate, Sodium Carbonate, Sodium Hydroxide, and Potassium Hydroxide in a solvent or mixture of solvents at a reaction temperature between 30°-50° C. at reduced pressure between 1.0 to 5.0 Kg/cm 2  to obtain crude Pyraclostrobin, compound of formula (I); and 
 
       
       
         
           
           
               
               
           
         
         
           ii) purifying the crude Pyraclostrobin of formula (I) obtained in step (i) in a suitable solvent or mixture of solvents. 
         
       
     
     
       2. The process as claimed in  claim 1 , wherein the methylating agent used in step (i) is Methyl chloride gas or Methyl bromide gas. 
     
     
       3. The process as claimed in  claim 2 , wherein the Mole ratio of methylating agent used for methylation reaction to the methyl[2-({[1-(4-chlorophenyl)-1H-pyrazol-3-yl]oxy}methyl)phenyl] hydroxycarbonate of formula (II) is in the range of 1 to 3.5. 
     
     
       4. The process as claimed in  claim 1 , wherein the reaction in step (i) is carried out in the presence of a catalyst that is Potassium Iodide and the ratio is 0.2 to 1.0% w/w on the basis of the methyl [2-({[1-(4-chlorophenyl)-1H-pyrazol-3-yl]oxy}methyl) phenyl] hydroxycarbamate of formula (II). 
     
     
       5. The process as claimed in  claim 1 , wherein the Mole Ratio of the acid binding agent to the methyl [2-({[1-(4-chlorophenyl)-1H-pyrazol-3-yl] oxy}methyl)phenyl]hydroxycarbamate of formula (II) is in the range of 1 to 1.5. 
     
     
       6. The process as claimed in  claim 1 , wherein the solvents used in step (i) are selected from acetone, methyl ethyl ketone, methyl isobutyl ketone, dichloromethane, dichloroethane, or mixture thereof. 
     
     
       7. The process as claimed in  claim 1 , wherein the solvent used in step (ii) for purifying the crude Pyraclostrobin obtained in step (i) is selected from Polyethylene glycol (PEG), Isopropyl Alcohol, hexane, or mixture thereof.